Role of Joseph

The exact meaning of the Gospel of Matthew's description of Joseph as a "just man" is much discussed; the Greek term is dikaios, and it has variously been translated as just, righteous, upright, and of good character. Most of the ancient commentators of the Bible interpreted it as meaning that Joseph was law abiding, and as such decided to divorce Mary in keeping with Mosaic Law when he found her pregnant by another, but, tempering righteousness by mercy, he intended to keep the situation private।A second view, first put forward by Clement of Alexandria, and held by many modern Christians is that Joseph's righteousness is his mercy itself, with the decision to ensure Mary was not shamed being proof of his righteousness rather than an exception to it.Joseph's original intent, though, was to divorce Mary once he had discovered her pregnancy, though some scholars and most older translations have expressed this more euphemistically since Joseph, a man having just been described as righteous, undergoing divorce would imply that divorce was righteous.
Recent discoveries have found that legal avenues for divorce certainly existed at the time in question. The Greek word here translated as divorce is aphiemi, and the only other time it appears is in 1 Cor 7:11 where Paul Tarsus uses it to describe the legal separation of a man and wife, and thus almost all modern translators today feel that divorce is what is being described, although doctrinal reasons cause some to use other wording.
In the first of several dream sequences in Matthew, an angel visits Joseph to dissuade him, and explain what has happened. The angel is described in a manner much more like early Jewish descriptions, as in the Pentateuch, merely as a pure functionary with no individuality, unlike the more esoteric descriptions that arose nearer the author's own time, under Hellenic influence, such as described in the Book of Enoch. Joseph carries out the angel's instructions exactly, rather than arguing with them, which appears to be a common theme in the Gospel—rapid and unquestioning obedience is treated in Matthew as an important virtue.